Many semiconductor processes employ process gases containing reactant materials that are used to form and/or treat semiconductor materials. For example, chemical vapor deposition (CVD) processes typically employ process gases to provide source materials for the growth and/or formation of thin layers of materials. Metal-organic CVD processes may use metal-organic process gases such as trimethyl gallium (TMG) and trimethyl aluminum (TMA) as source gases for gallium and aluminum, respectively. Halides, such as BCl3, and other materials, such as silane (SiH4), may be used in CVD processes. Fluorine-based gases, such as NF3 and SF6, may also be used in semiconductor processing operations.
In a CVD process, reactant gases are generally flowed across a growth substrate in a reaction chamber at a high temperature. The reactant gases may decompose near the growth substrate and deposit on the substrate to form a layer of material on the substrate. The CVD reaction may generate a number of waste byproducts (components), such as unreacted components of reactant gases, carrier gases, reaction byproducts, and/or other waste components. These waste components are typically flushed from the reaction chamber through an exhaust tube and/or vent during and/or after the semiconductor processing.
Many gases used in semiconductor processes, and the gaseous byproducts of the semiconductor processes, may pose health and/or environmental hazards. Thus, exhaust gases generated by semiconductor processes are typically treated to reduce such potential hazards. Exhaust gases may be treated, for example, using a thermal processing unit (TPU) that may thermally decompose exhaust gases. A TPU, which may be electrically-fired and/or fuel-fired, may be configured to combust exhaust gases and scrub the combusted gases to reduce hazardous air pollutants.
Conventionally, a TPU is coupled to a semiconductor processing tool by means of a TPU inlet tube, which receives exhaust gases generated in the tool. Waste byproducts in the exhaust gases may build up as deposits in the inlet tube, which may cause the inlet tube to become partially and/or completely blocked. It may be difficult and/or time-consuming to clean and/or replace an inlet tube of a TPU. Moreover, to clean and/or replace an inlet tube of a TPU, it may be necessary to inactivate the semiconductor processing equipment that uses the TPU, which may result in significant expense and/or loss of equipment utilization.
In conventional systems, it is known to use a pneumatic piston to scrape built-up waste deposits from the inside of a TPU inlet tube. Although such conventional approaches may reduce build-up of waste materials in a TPU inlet tube, such approaches have not been entirely successful, with the result that it may frequently be necessary to manually clean a TPU inlet tube, even when such approaches are employed.